Overview
This document describes using the XMOS USB Device (XUD) Library and provides a worked example of a USB Human Interface Device (HID) Class compliant mouse using the library.
This library is aimed primarily for use with xCORE-USB (U-Series) devices but it does also support L-Series devices (see L-Series support).
For full XUD API listing and documentation please see the document XMOS USB Device (XUD) Library.
This document assumes familiarity with the XMOS xCORE architecture, the Universal Serial Bus 2.0 Specification (and related specifications), the XMOS tool chain and XC language.
Features
- Support for USB 2.0 full and high speed devices.
Memory requirements
The approximate memory usage for the USB device module including the XUD library is as follows:
Usage |
|
|---|---|
Stack |
2kB |
Program |
12kB |
Resource requirements
The resources used by the device application and libraries on the xCORE-USB are shown below:
Resource |
Requirements |
|---|---|
Logical Cores |
2 plus 1 per endpoint |
Channels |
2 for Endpoint0 and 1 additional per IN and OUT endpoint |
Timers |
4 timers |
Clock blocks |
Clock blocks 4 and 5 |
Core speed
Due to I/O timing requirements, the library requires a guaranteed MIPS rate to ensure correct operation. This means that core count restrictions must be observed. The XUD core must run at at least 80 MIPS.
This means that for an xCORE device running at 500MHz no more than six cores shall execute at any one time when using the XUD.
This restriction is only a requirement on the tile on which the XUD is running. For example, a different tile on an U16 device is unaffected by this restriction.
Ports and pins
The U-Series of processors has an integrated USB transceiver. Some ports are used to communicate with the USB transceiver inside the U-Series packages. These ports/pins should not be used when USB functionality is enabled. The ports/pins are shown in the table below.
Pin 1b |
Port 4b |
||||
|---|---|---|---|---|---|
X0D02 |
P4A0 |
P8A0 |
P16A0 |
P32A20 |
|
X0D03 |
P4A1 |
P8A1 |
P16A1 |
P32A21 |
|
X0D04 |
P4B0 |
P8A2 |
P16A2 |
P32A22 |
|
X0D05 |
P4B1 |
P8A3 |
P16A3 |
P32A23 |
|
X0D06 |
P4B2 |
P8A4 |
P16A4 |
P32A24 |
|
X0D07 |
P4B3 |
P8A5 |
P16A5 |
P32A25 |
|
X0D08 |
P4A2 |
P8A6 |
P16A6 |
P32A26 |
|
X0D09 |
P4A3 |
P8A7 |
P16A7 |
P32A27 |
|
X0D23 |
P1H0 |
||||
X0D25 |
P1J0 |
||||
X0D26 |
P4E0 |
P8C0 |
P16B0 |
||
X0D27 |
P4E1 |
P8C1 |
P16B1 |
||
X0D28 |
P4F0 |
P8C2 |
P16B2 |
||
X0D29 |
P4F1 |
P8C3 |
P16B3 |
||
X0D30 |
P4F2 |
P8C4 |
P16B4 |
||
X0D31 |
P4F3 |
P8C5 |
P16B5 |
||
X0D32 |
P4E2 |
P8C6 |
P16B6 |
||
X0D33 |
P4E3 |
P8C7 |
P16B7 |
||
X0D34 |
P1K0 |
||||
X0D36 |
P1M0 |
P8D0 |
P16B8 |
||
X0D37 |
P1N0 |
P8C1 |
P16B1 |
||
X0D38 |
P1O0 |
P8C2 |
P16B2 |
||
X0D39 |
P1P0 |
P8C3 |
P16B3 |
||